import collections
N,M = map(int,input().split())

lsg = [[] for i in range(N)]
cntn = [0]*(N)
eki = set()

for i in range(M):
    a,b = map(int,input().split())
    lsg[a].append(b)
    lsg[b].append(a)
    cntn[a] += 1
    cntn[b] += 1
    eki.add(a)
    eki.add(b)
l =list(eki)
d = collections.deque([l[0]])
used = [False]*N

while d:
    v = d.popleft()
    if used[v]:
        continue
    used[v] = True
    for j in lsg[v]:
        if used[j]:
            continue
        d.append(j)

if used.count(True) != len(eki):
    print('NO')
    exit()

evencnt = 0

for i in eki:
    if cntn[i] % 2 == 1:
        evencnt += 1

if evencnt <= 2:
    print('YES')
else:
    print('NO')